There are different reasons behind Independence Day celebrations on August 14 in Pakistan.
The separate states of India and Pakistan were created at midnight on August 15, 1947. Yet while India celebrates that day as its independence day, Pakistan celebrates its independence day a day before. Why it is so?
Pakistan's first Independence Day was also celebrated on August 15 but later on it was advanced to August 14. One of the reasons is that British Viceroy Lord Mountbatten, who had chosen August 15 to commemorate the surrender of Japan to the Allies Power marking the end of World War II in 1945, sought to transfer power to Pakistan on August 14 so that he could be present in New Delhi to observe India's maiden independence day celebrations.
Pakistan decided to celebrate its Independence Day on August 14 because 27 Ramadan, an auspicious date of the Islamic lunar calendar, coincided with it. Hence the Pakistanis decided to celebrate their Independence Day a day before the actual date. But otherwise, August 15 is the actual Independence Day for both India and Pakistan (Even South Korea observes its Liberation Day on August 15). The Indian Independence Act of 1947 clearly said: "As from the fifteenth day of August, nineteen hundred and forty-seven, two independent Dominions shall be set up in India, to be known respectively as India and Pakistan." Even Pakistan's founding father Muhammad Ali Jinnah had declared August 15 as the birthday of the independent and sovereign state of Pakistan. The first commemorative postage stamps of Pakistan which were released in July 1948 also mentioned 15 August 1947 as its Independence Day.